This invention relates to a synchronizer having multiple friction cones and self-energizing.
A Synchronizer with multiple friction cones and self-energizing may be seen by reference to the baulkring-type synchronizer in U.S. Pat. No. 5,135,087. This synchronizer includes friction and jaw members for synchronizing and positively clutching a gear to a shaft, pre-energizer assemblies for engaging the friction members in response to an operator shift force effecting initial engaging movement of a shift sleeve, a hub rotatably fixed to the shaft and having external spline teeth slidably receiving internal spline teeth of the shift sleeve which defines one of the jaw members, and a baulkring having blocker teeth for arresting engaging movement of the shift sleeve until synchronization is reached and for transferring a shift force from the sleeve to increase the engaging force of the friction members to a force proportional to operator shift force. The friction members include a middle friction member that rotates with the gear and that is sandwiched between outer and inner friction rings in fixed rotation with hub. The middle friction ring includes torque drive tangs having cam surfaces that engage cam surfaces fixed to the gear. Engagement of these cam surfaces during synchronizing draws the middle friction ring toward the inner friction ring thereby increasing the engagement force there between to provide a first additive force or self-energizing force proportional to the synchronizing torque.
An object of this invention is to provide improved self-energizing for a synchronizer with multiple friction cones.
According to a feature of the invention, a synchronizer is for first and second drives disposed for rotation about a common axis and secured against axial movement relative to each other. The synchronizer includes a hub affixed to the first drive and having external splines. A shift sleeve includes internal spines continuously mating with the hub external splines and is selectively engagable with external splines affixed to the second drive in response to engaging movement of the shift sleeve by a first shift force. The shift sleeve has first blocker surfaces. A first inner ring has an external cone friction surface. A first cone member is rotatable with the second drive and has external and internal cone friction surfaces. A first baulkring is mounted for limited rotation relative to the hub and has an internal cone friction surface and second blocker surfaces. Pre-energizer means is for engaging the baulkring and inner ring friction surfaces respectively with the cone member external and internal friction surfaces in response to initial engaging movement of the shift sleeve by the first shift force and for positioning the blocker surfaces for engagement to prevent asynchronous engagement of the shift sleeve and second drive splines, and to transmit the first shift force to the engaged friction surfaces with an engaging force producing a synchronizing torque. Self-energizing means is operative to react the synchronizing torque for producing a first additive force in the direction of the first shift force for increasing the engagement force of the engaged friction surfaces.
The improvement comprising the first inner ring mounted for limited rotation relative to the hub and having first ramp means; and the self-energizing means including a boost member disposed in a radially extending opening in the hub and moved radially outward by the first ramp means in response to the synchronizing torque, and the boost member having a first boost surface engagable with a second boost surface affixed to the shift sleeve for producing the first additive force.